public interface Leetcode_12 {
    public static void main(String[] args) {
        String s = "abcd";
        String t = "abcde";

        int[] cnt = new int[26];
        for (int i = 0; i < s.length(); ++i) {
            char ch = s.charAt(i);
            cnt[ch - 'a']++;
        }
        for (int i = 0; i < t.length(); ++i) {
            char ch = t.charAt(i);
            cnt[ch - 'a']--;
            if (cnt[ch - 'a'] < 0) {
                System.out.println(ch);
            }
        }
        System.out.println(" ");
    }
}
